Stuffing machines are known which automatically stuff food product, such as emulsion, into a casing length deshirred from a shirred supply, gather the end after the product is stuffed, apply a second tie clip, apply a first tie clip for a subsequent product, and then sever the product from the casing supply.
One such stuffing apparatus which has generally been well accepted, and which is capable of precisely controlling the stuffed diameter of the product is described and claimed in Kupcikevicius et al U.S. Pat. No. Re. 30,390. In that apparatus, a sizing disc or ring is used to stretch the casing to about its recommended stuffed diameter just prior to filling the casing with emulsion. After the desired casing length is stuffed, a gathering and clipping operation is performed immediately adjacent the discharge end of the stuffing horn. A set of gathering gates constricts the casing following which a second tie clip is applied. In order to facilitate the gathering operation without causing an undesirable increase in stuffing pressure, a tension sleeve on the stuffing horn is reciprocated fore and aft to create a predetermined length of slack casing which can be drawn upon as the gathering gates constrict the sausage end. Because the gathering and second tie clipping is performed immediately adjacent the discharge end of the stuffing horn, the application of the first tie clip to the end of the casing supply must be performed in a later part of the cycle, after the clipper head is indexed to bring the first tie clipper into play. Such a sequential clipping cycle tends to extend the cycle length. This is not a serious drawback in the production of relatively large slicing size sausages, where careful application of the second tie clip is important, because a significant portion of the overall cycle is used in the actual stuffing operation. However, as the sausages become shorter in length and smaller in circumference, the clipping cycle becomes a more significant proportion of the overall stuffing cycle.
The casing which is commercially used in this stuffing system (U.S. Pat. No. Re. 30,390) is controllably premoisturized by the casing manufacturer and provides several advantages. First of all, there is no need to soak the casing stick at the processing plant immediately prior to stuffing. This yields a significant advantage with respect to convenience, in that the time, equipment, and effort heretofore used in soaking the casing prior to stuffing is eliminated. Furthermore, with the moisture content of the casing being at a controlled level, the casing tends to behave in a predictable fashion on the stuffing machine. Finally, because soaking just prior to stuffing is not a requirement, the casing can be shirred to higher pack ratios, so that a greater length of casing can be shirred into a stick of predetermined length, thereby reducing stuffing machine down time due to stick loading.
A second type of automatic stuffing machine, popular for at least some applications such as chubbing, is known as the Polyclip FCA-S (Model 3451), and aspects thereof are generally described in Niedecker U.S. Pat. Nos. 3,748,690 and 3,872,543. The cycle time for the clipping cycle in this chubbing machine is reduced by applying the second tie clip to the stuffed product and the first tie clip to the casing end simultaneously. However, such simultaneous operation prevents the clipping mechanism from gathering the encased product immediately adjacent the stuffing horn. In practice, a pair of closely spaced gathering gates contact the stuffed product at about its fully stuffed circumference to gather the casing, then separate laterally to provide room for applying a pair of clips. During the course of constricting and lateral separation, some of the stuffed emulsion must be displaced. The machine achieves casing holdback with an external snubbing device which can be advanced to effectively release the holdback so that casing can be drawn from the thus-released supply to accommodate the displaced emulsion.
As a result of using external holdback, however, the only mechanism available for stretching the casing to size is the meat mass entering the casing. This has been found acceptable for fully soaked casing, because such casing is relatively pliable and can thus be stretched to size by the meat mass. It has been found, however, that when using this approach with controllably premoisturized casing which is much less pliable, stuffing pressure is raised to levels which often cause the casing to break or the first tie clip to fail.
More particularly, casing which is controllably premoisturized to a commercially acceptable level (for example about 20 wt. %) is much less pliable than fully soaked casing. As a result, stuffing pressures with premoisturized casing can be higher on the FCA-S chubbing machine than those encountered with fully soaked casing by a factor of 2 or 3. This substantially increased stuffing pressure magnifies any problems with retention of clips on the product, problems which are particularly acute when stuffing short chubs.
In order to stuff controllably premoisturized casing on such a chubbing machine, while at the same time limiting stuffing pressures to levels which will not cause the casing or clip to fail, it has been found most advantageous to use a sizing ring as described in Beckman U.S. Pat. No. 4,007,761, incorporated herein by reference. The sizing ring circumference is selected to stretch the casing to about its recommended stuffed diameter so that emulsion entering the casing need only fill the casing while causing little, if any, additional stretching.
Unfortunately, disposing a sizing ring within the casing to stretch the casing to size on the chubbing machine creates additional problems since the sizing ring establishes an additional holdback force which is excessive when combined with the holdback force of the previously discussed FCA-S snubbing device.
In the machine described in the afore-mentioned U.S. Pat. No. Re. 30,390, a slacking arrangement is provided in which a reciprocating pneumatic cylinder cycles a tension sleeve fore and aft to create a controlled length of slack casing which, in effect, substantially reduces the holdback force for that slack length. The slack casing is available to be drawn by the gathering gates in the gathering and clipping operation. The cycle time attributed to the gathering and second tie clip application in the U.S. Pat. No. Re. 30,390 apparatus is on the order of 1 or 2 seconds, allowing the use of double-acting pneumatic cylinder to reciprocate the tension sleeve. A direct application of this slacking approach to the simultaneous double clipper of the FCA-S chubbing machine would require an unacceptable extension of the clipping cycle time.
Use of the U.S. Pat. No. 4,007,761 sizing ring concept involves passing the casing over the sizing ring and through a sealing ring (which prevents emulsion back flow) whereupon it is filled with food product from the stuffing horn. In order to adjust the stuffing pressure to achieve a desired product size, the distance between the sizing ring and sealing ring is adjustable to vary the casing angle between the two rings to produce a specific holdback force of a magnitude sufficient to cause the casing to fill to the desired size.
When the desired amount of product is stuffed into the casing, the food pump is de-energized and the relationship between the sizing and sealing rings continues to oppose the pressure within the product which was created by the original holdback force. If gathering and clipping were attempted in that condition, an unacceptable product pressure buildup would occur.